I have a ’09 G8 GT and I have been disappointed with the stereo since I bought the car. I have always thought that any stereo with two 8’s in the rear deck that there should be more. After playing with all the radio settings and playing different types of music, I could not seem the get that punch that ought to be there (well as much as can be expected for a stock system). It always sounds “off”. I was about to go ahead and pull out the stock stuff like a lot of people have, but I was having one last overview of the system before I spent money on it, but it dawned on me that the “off” sound was like the system was out of phase.
Well I am happy to report that I have solved the crappy stock stereo mystery (at least on my vehicle). The two subs in the rear deck are out of phase with the speakers driven by the head unit. After doing a quick swap of the wire position on each sub, WOW the system absolutely cranks compared to before.
On my car I switched the position of the yellow and green wire on each sub so now the yellow wires are closest to the rear seat and the green wires are closer to the tail lights.
Man - give it a try before upgrading, you might be surprised and save some money……